Most bicycle owners equip their bicycles with a carrier rack, more often with a rear carrier rack, but in some cases a front carrier rack. Experienced bicycle riders know that a carrier rack must be as rigid and as rigidly attached to the bicycle as possible, lest a load carried on the rack sway from side to side and make it more difficult to control the bicycle. A swaying load will require the rider to be much more attentive to steering and balance than he or she otherwise would be, and the rider will tire much more quickly when riding a bicycle with a heavy load that sways from side to side. Many bicycle carrier racks on the market today are not sufficiently strong and not adequately secured to the bicycle to prevent substantial swaying, even with comparatively light loads. When the rack carries loaded panniers, sleeping bags and other articles required for bicycle touring, it is virtually essential that the bicyclist have a very rigid, high quality carrier rack.
U.S. Pat. No. 4,154,382, issued May 15, 1979, and entitled "Bicycle Rack" describes and illustrates a rear carrier rack made of bent metal rods that define the platform frame and three inverted U-shaped struts and that are joined together by welding. The carriers described in that patent are strong and rigid and, as manufactured and marketed in substantially the forms described and illustrated in the patent, are generally acknowledged to be of high quality. On the other hand, they have some disadvantages. For one thing, the unitized construction virtually eliminates the possibility of repairing a carrier, should there be some failure, particularly a weld failure or a broken or severely bent frame or strut. Any bent or broken part cannot be replaced and if that part cannot be repaired, the carrier will have to be discarded. Also, they must be packaged, shipped, stocked and sold in large cumbersome boxes.
The patent describes and illustrates two forms of the carrier, one of which provides for three point attachment to the bicycle and the other of which provides for four point attachment. In the three point version, a bent metal connecting strip can be adjusted longitudinally along a supporting guide that extends lengthwise along the center line of the carrier and is welded to a pair of longitudinally spaced-apart cross pieces of the frame. The connector strip has a lengthwise slot through which screws that pass through the guide bar extend, and nuts threaded on the screws under the connector piece clamp the connector piece in a desired position. The front end of the connector strip turns downwardly and is shaped and positioned to be connected to the bolt that fastens the rear brake caliper to the bicycle frame. This adjustable single point front attachment provides very little resistance to swaying of the rack by pivoting about the single front attachment point.
In the other version of carrier described and shown in the above-mentioned patent, two connecting bars constituted by forwardly extending legs of a U-shaped member welded to the cross pieces enable the carrier rack to be connected to the seat stays using ring clamps or special fittings brazed to the seat stays. This version allows, therefore, four point attachment of the carrier to the bicycle, and the two connecting points at the front do not allow the pivoting type of swaying to nearly the extent of the single front-connecting point version. On the other hand, a given four point carrier rack will not properly fit many popular commercially available bicycles, inasmuch as the four connecting points are geometrically and dimensionally fixed, whereas the positions of the seat stays and the accessory holes near the rear axle where the lower ends of the struts are attached differ among different sizes and makes of bicycles.